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            Bearing Grease Degradation Related to Water and Roller Bluing
      

      
  Document Series
              Technical Reports


      
  Author
          Federal Railroad Administration


      
Report Number
              DOT/FRA/ORD-23/33

  Office
              RDI-22


      Subject
                    Rolling Stock


      
  Keywords
              Coupler, knuckle, failure, fatigue, fracture, life calculation, load case combination, stress, tensile strength, train operatio Roller bearings, water-etch, non-verified bearing failure, testing, rolling stock, lube stain, grease


      

      
      
              
                  
      
              
  Document
              Bearing Grease Degradation to Water and Roller Bluing Report.pdf (897.46 KB)

      
              The Federal Railroad Administration sponsored a team from Transportation Technology Center, Inc. to conduct two investigations to improve the safety of roller bearing operations on railcars. The team conducted the research between September 2018 and April 2022 in collaboration with Burlington Northern Santa Fe Railway, Timken Company, and Amsted Rail Company, Inc. to provide insight into the internal state of bearings that have degraded due to grease degradation from water ingress. The tests conducted in the investigation of water ingress-related bearing grease degradation indicated a difference between bearings with “Water-Etch” and “Non-Verified” failure modes based on ferrous debris levels in the grease. This difference is due to wear of the bearing material deposited in the grease. The tests conducted in the investigation of lube stain in bearings showed lube stain does not affect any tested metallurgical material properties other than surface discoloration. The team recommends that further grease samples should be taken to allow statistical inference of other variables other than ferrous wear, including contamination, consistency, and moisture levels.
      
            
      
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              Last updated: Thursday, September 28, 2023 U.S. DEPARTMENT OF TRANSPORTATION

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